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| 1 /* Copyright 2016 Google Inc. All Rights Reserved. |
| 2 |
| 3 Distributed under MIT license. |
| 4 See file LICENSE for detail or copy at https://opensource.org/licenses/MIT |
| 5 */ |
| 6 |
| 7 #ifndef BROTLI_COMMON_CONSTANTS_H_ |
| 8 #define BROTLI_COMMON_CONSTANTS_H_ |
| 9 |
| 10 /* Specification: 7.3. Encoding of the context map */ |
| 11 #define BROTLI_CONTEXT_MAP_MAX_RLE 16 |
| 12 |
| 13 /* Specification: 2. Compressed representation overview */ |
| 14 #define BROTLI_MAX_NUMBER_OF_BLOCK_TYPES 256 |
| 15 |
| 16 /* Specification: 3.3. Alphabet sizes: insert-and-copy length */ |
| 17 #define BROTLI_NUM_LITERAL_SYMBOLS 256 |
| 18 #define BROTLI_NUM_COMMAND_SYMBOLS 704 |
| 19 #define BROTLI_NUM_BLOCK_LEN_SYMBOLS 26 |
| 20 #define BROTLI_MAX_CONTEXT_MAP_SYMBOLS (BROTLI_MAX_NUMBER_OF_BLOCK_TYPES + \ |
| 21 BROTLI_CONTEXT_MAP_MAX_RLE) |
| 22 #define BROTLI_MAX_BLOCK_TYPE_SYMBOLS (BROTLI_MAX_NUMBER_OF_BLOCK_TYPES + 2) |
| 23 |
| 24 /* Specification: 3.5. Complex prefix codes */ |
| 25 #define BROTLI_REPEAT_PREVIOUS_CODE_LENGTH 16 |
| 26 #define BROTLI_REPEAT_ZERO_CODE_LENGTH 17 |
| 27 #define BROTLI_CODE_LENGTH_CODES (BROTLI_REPEAT_ZERO_CODE_LENGTH + 1) |
| 28 /* "code length of 8 is repeated" */ |
| 29 #define BROTLI_INITIAL_REPEATED_CODE_LENGTH 8 |
| 30 |
| 31 /* Specification: 4. Encoding of distances */ |
| 32 #define BROTLI_NUM_DISTANCE_SHORT_CODES 16 |
| 33 #define BROTLI_MAX_NPOSTFIX 3 |
| 34 #define BROTLI_MAX_NDIRECT 120 |
| 35 #define BROTLI_MAX_DISTANCE_BITS 24U |
| 36 /* BROTLI_NUM_DISTANCE_SYMBOLS == 520 */ |
| 37 #define BROTLI_NUM_DISTANCE_SYMBOLS (BROTLI_NUM_DISTANCE_SHORT_CODES + \ |
| 38 BROTLI_MAX_NDIRECT + \ |
| 39 (BROTLI_MAX_DISTANCE_BITS << \ |
| 40 (BROTLI_MAX_NPOSTFIX + 1))) |
| 41 |
| 42 /* 7.1. Context modes and context ID lookup for literals */ |
| 43 /* "context IDs for literals are in the range of 0..63" */ |
| 44 #define BROTLI_LITERAL_CONTEXT_BITS 6 |
| 45 |
| 46 /* 7.2. Context ID for distances */ |
| 47 #define BROTLI_DISTANCE_CONTEXT_BITS 2 |
| 48 |
| 49 /* 9.1. Format of the Stream Header */ |
| 50 /* Number of slack bytes for window size. Don't confuse |
| 51 with BROTLI_NUM_DISTANCE_SHORT_CODES. */ |
| 52 #define BROTLI_WINDOW_GAP 16 |
| 53 |
| 54 #endif /* BROTLI_COMMON_CONSTANTS_H_ */ |
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